From: 7willows at dsl dot pipex dot com
Operating system: SunOS ts10 5.11 snv_115 i86pc
PHP version: 5.2.10
PHP Bug Type: Math related
Bug description: multiplication by zero problem
Description:
------------
I have a function which is used to assign values into a number of global
arrays. Two of the arrays are assigned values that are generated using the
rand() function. A third array holds the result of the multiplication. When
both first two arrays are assigned a value of 0 (zero), the result of the
multiplication is 1 and not 0.
This information is then entered into a html form and presented to the
user and they are asked to enter the results of
$numfacttest[$a] / $randval[$a] = useranswer
The useranswer is then compared to $answer[$a] which is already
calculated. The problem is that 0 * 0 is returning the answer 1 sometimes.
Reproduce code:
---------------
function setnumberfacttest($count,$maxnumberfacts) {
global $numfacttest, $answer, $operator, $randval;
for ($a=0 ; $a < $count ; $a++) {
$operator[a]=chr(247);
$bit1=rand(0,$maxnumberfacts);
$bit2=rand(0,$maxnumberfacts);
$numfacttest[$a]=$bit1 * $bit2;
$randval[$a]=$bit2;
$answer[$a]=$bit1;
}
}
Expected result:
----------------
Actual Results with hidden value displayed
2 / 1 = <useranswer> 2
0 / 0 = <useranswer> 0
0 / 0 = <useranswer> 0
2 / 2 = <useranswer> 1
4 / 2 = <useranswer> 2
1 / 1 = <useranswer> 1
0 / 0 = <useranswer> 0
0 / 0 = <useranswer> 0
0 / 0 = <useranswer> 0
1 / 1 = <useranswer> 1
Actual result:
--------------
Actual Results with calculated hidden value displayed
2 / 1 = <useranswer> 2
0 / 0 = <useranswer> 1
0 / 0 = <useranswer> 0
2 / 2 = <useranswer> 1
4 / 2 = <useranswer> 2
1 / 1 = <useranswer> 1
0 / 0 = <useranswer> 1
0 / 0 = <useranswer> 0
0 / 0 = <useranswer> 2
1 / 1 = <useranswer> 1
--
Edit bug report at http://bugs.php.net/?id=48904&edit=1
--
Try a CVS snapshot (PHP 5.2):
http://bugs.php.net/fix.php?id=48904&r=trysnapshot52
Try a CVS snapshot (PHP 5.3):
http://bugs.php.net/fix.php?id=48904&r=trysnapshot53
Try a CVS snapshot (PHP 6.0):
http://bugs.php.net/fix.php?id=48904&r=trysnapshot60
Fixed in CVS:
http://bugs.php.net/fix.php?id=48904&r=fixedcvs
Fixed in CVS and need be documented:
http://bugs.php.net/fix.php?id=48904&r=needdocs
Fixed in release:
http://bugs.php.net/fix.php?id=48904&r=alreadyfixed
Need backtrace:
http://bugs.php.net/fix.php?id=48904&r=needtrace
Need Reproduce Script:
http://bugs.php.net/fix.php?id=48904&r=needscript
Try newer version:
http://bugs.php.net/fix.php?id=48904&r=oldversion
Not developer issue:
http://bugs.php.net/fix.php?id=48904&r=support
Expected behavior:
http://bugs.php.net/fix.php?id=48904&r=notwrong
Not enough info:
http://bugs.php.net/fix.php?id=48904&r=notenoughinfo
Submitted twice:
http://bugs.php.net/fix.php?id=48904&r=submittedtwice
register_globals:
http://bugs.php.net/fix.php?id=48904&r=globals
PHP 4 support discontinued: http://bugs.php.net/fix.php?id=48904&r=php4
Daylight Savings: http://bugs.php.net/fix.php?id=48904&r=dst
IIS Stability:
http://bugs.php.net/fix.php?id=48904&r=isapi
Install GNU Sed:
http://bugs.php.net/fix.php?id=48904&r=gnused
Floating point limitations:
http://bugs.php.net/fix.php?id=48904&r=float
No Zend Extensions:
http://bugs.php.net/fix.php?id=48904&r=nozend
MySQL Configuration Error:
http://bugs.php.net/fix.php?id=48904&r=mysqlcfg
